Unit 2 Flashcards
What is the biological species concept?
A species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring with members of other such groups
What are the limitations of the biological species concept?
It does not account for hybridization or asexually reproducing organisms.
What can lead to speciation?
A reduction of gene flow because it holds populations together genetically since it occurs between different populations of groups and species.
Explain how species distribution reveals evolutionary events?
Biogeography can help to understand the relations between species. For example, in the Philippines and in Japan, islands closer to Asia have species more closely related to those found there. Islands closer to Australia have species more related to those found there as well.
Explain how anatomical comparisons reveal evolutionary events.
Homology for structures and genes can reveal the close relations of species. Along with homology, the role of habitat and comparative relations with other organisms plays a role too in order to distinguish between homology and homoplasty, in which similar structures and genes came about by chance in order to adapt to the organisms’ similar environments or circumstances.
Explain how DNA and protein sequence comparisons reveal evolutionary events.
Species with a large amount of similar DNA and protein sequences are more likely to be closely related.
What is an ancestral trait and where might you find it on a cladogram?
A characteristic originated in an ancestor of a taxon Ex. Backbones in mammals
This could be traced back to the first common ancestor that has the characteristic on the cladogram.
What is a derived trait and where can this be found on a cladogram?
An evolutionary novelty unique to a clade Ex. Mammal’s hair
The first organism that exhibits this unique trait.
What is an out group?
A species or groups of species from an evolutionary lineage that is closely related to but not part of the group of species being studied.
What is a clade and where can it be found on the cladogram?
A branch that includes a single common ancestor and all of its descendants
What is a common ancestor and where would you find that in a cladogram?
A common ancestor is a species that appeared earlier in evolutionary history that diverged into 1 or more groups. In a cladogram, a common ancestor can be identified by nodes, and if the cladogram is rooted with a branch point at the end of the tree, that point represents the most recent common ancestor of all the taxa of the tree.
What is homoplasy?
Similarities between organisms that is due to convergent evolution
What is convergent evolution?
Similar environmental pressures and nature selection produce similar adaptations in organisms with different evolutionary lineages.
When can you determine whether two organisms are analogous versus homologous?
The more elements in two complex structures or genes that are similar, the more likely there’s a common ancestor. However, if other organisms that descend after the two groups in question have diverged do not share those traits being studied, it is likely they are analogous that arose through coincidence or similar environmental conditions.
What is a monopolistic group?
Consists of an ancestor and ALL of its descendants
This is the only irme when a taxon is equal to a clade.
What is a polyphyletic group?
Includes distantly related species and not their most recent common ancestor
What is a paraphyletic group?
Consists of an ancestral species and some of its descendants
Explain how biodiversity results from speciation and extinction events on both local and global scales.
Speciation results in biodiversity by diverging one species into 1 or more unique groups. This adds to diversity locally when it happens within a specific local area as a result of the availability of new niches or random environmental events or even sympatric or parapatric speciation. Globally, speciation adds to diversity through the movement of organisms like with the Galapagos finches, which results in natural selection. Extinction can also add to biodiversity, because the surviving organisms can fill in the newly available niches, leading to adaptive radiation.
Differentiate between the different types of speciation through degrees of physical separation.
Allopatric- physical isolation
Parapatric- lives in different habitats of same area
Sympatric- live in same habitat/area
When does allopatric speciation occur?
when there is a founder population or an environmental change that results in physical barriers
What is parapatric speciation?
Speciation that occurs despite the potential for gene flow between neighboring groups. This means that other forces of evolution are stronger than forces of gene flow. Ex. Land and marine iguanas
What forces can allow for sympatric speciation?
The availability of different niches allows for natural selection (Galapagos finches), habitat isolation, sexual selection (chiclids), and polyploidy
What are homologous structures?
Ones possessed by different organisms because they both inherited their structures from a common ancestor
What is the relationship between biodiversity and speciation?
There is a direct relationship. Speciation directly leads to the creation of multiple unique species from one.
